Decades-Old Diabetes Drug Metformin Found to Work on Brain, Opening Door to New Therapies

For over 60 years, Metformin has served as a foundational treatment for millions of people managing type 2 diabetes. While physicians have long understood that the drug manages blood sugar, the precise mechanics of how it functions have remained partially obscured. Now, a breakthrough study suggests the medication works directly on the brain, a revelation that could pave the way for entirely new treatment methods.

Researchers at the Baylor College of Medicine have identified a specific neural pathway utilized by the drug. While medical consensus previously held that Metformin operated primarily on biological processes within the gut and liver, these new findings indicate the brain plays a pivotal role.
“It’s been widely accepted that metformin lowers blood glucose primarily by reducing glucose output in the liver. Other studies have found that it acts through the gut,” Makoto Fukuda, a pathophysiologist at Baylor and lead researcher on the study told Science Alert.

Fukuda noted that the team decided to pivot their focus to the central nervous system. “We looked into the brain as it is widely recognized as a key regulator of whole-body glucose metabolism. We investigated whether and how the brain contributes to the anti-diabetic effects of metformin.”

The study, published in the journal Science Advances, details how the research team focused on the ventromedial hypothalamus (VMH), a section of the brain previously linked to glucose metabolism.

In tests conducted on mice, the researchers observed Metformin traveling to the VMH and interacting with a protein known as Rap1. The drug essentially “turns off” this protein to combat diabetes symptoms. To confirm this mechanism, the team bred mice lacking the Rap1 protein. When these specific mice were treated with Metformin, the drug failed to impact their diabetes-like condition, whereas other medications remained effective.

This isolation of the Rap1 protein provides strong evidence that Metformin relies on a unique brain-based mechanism distinct from other treatments. Furthermore, the team identified the specific neurons involved.
“We also investigated which cells in the VMH were involved in mediating metformin’s effects,” said Fukuda. “We found that SF1 neurons are activated when metformin is introduced into the brain, suggesting they’re directly involved in the drug’s action.”

This discovery offers potential for the future of diabetes management. By understanding that the drug targets specific neurons, scientists may be able to develop treatments that are far more targeted.

This new understanding may also shed light on previous studies linking Metformin to slowed brain aging and increased lifespan. While the current results were observed in animal models, human trials are the necessary next step. If the findings translate to humans, researchers believe they could find ways to boost the potency of Metformin or develop therapies that mimic this brain-centric pathway.
“This discovery changes how we think about metformin,” Fukuda concluded. “It’s not just working in the liver or the gut, it’s also acting in the brain.”